Portable devices, such as mobile phones and tablet computers, are typically utilized to execute a wide variety of different applications. With the integration of inertial sensors, such as accelerometers and gyroscopes, into portable devices, functionality is provided for detected device movements. Accordingly, there is an opportunity for improved portable devices and associated applications that make use of inertial sensors. Additionally, there is an opportunity for portable device applications that identify and process user activities based at least in part upon detected motion and/or orientation in combination with contextual information associated with a portable device environment.